1. Field of the Invention
The present invention relates generally to protective coatings and, in one particular embodiment, to a flexible siloxane-based polymeric coating incorporating a hybrid copolymer.
2. Technical Considerations
In the aviation industry, aircraft windows commonly incorporate a plastic substrate, such as a polycarbonate or stretched acrylic substrate. These plastic substrates provide excellent safety performance and are lighter than conventional glass substrates, which decreases the overall weight of the aircraft. It is known to apply a protective, abrasion-resistant coating onto the plastic substrate to protect the substrate from mechanical and/or chemical damage during aircraft operation. For example, some commercially available protective coatings contain colloidal silica. However, these commercial coatings can exhibit poor resistance to solvents, such as acetone and sulfuric acid. Other commercially available protective coatings are based on relatively soft organic polymer systems, such as urethanes or melamines.
In an effort to improve the protection to the underlying substrate, harder, more durable polysiloxane-based coatings were developed. These harder coatings provide much improved protection compared to the previous softer coatings. However, these hard coatings are by nature less flexible than the prior softer coatings.
Therefore, it would be advantageous to provide a protective coating that provides not only excellent scratch, abrasion, and chemical resistance of a polysiloxane coating but also improved flexibility to better withstand elongation or deformation of the plastic substrate that can occur during aircraft operation.